High telomerase activity bone marrow mesenchymal stem cells, methods of producing the same and pharmaceuticals and treatment methods based thereon

ABSTRACT

Disclosed are isolated human bone marrow mesenchymal stem cells having high telomerase activity (tBMMSCs). Also disclosed are isolated human CD34 +  bone marrow mesenchymal stem cells. Also disclosed are bone marrow mesenchymal stem cells treated with a telomerase induction agent.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional application of U.S. patent applicationSer. No. 13/810,878, filed Aug. 22, 2013, entitled “High TelomeraseActivity Bone Marrow Mesenchymal Stem Cells, Methods of Producing theSame and Pharmaceuticals and Treatment Methods Based Thereon,” attorneydocket 064693-0343; which is a United States national phase applicationof PCT Application PCT/US11/44731, filed Jul. 20, 2011, entitled HighTelomerase Activity Bone Marrow Mesenchymal Stem Cells, Methods ofProducing the Same and Pharmaceuticals and Treatment Methods BasedThereon,” attorney docket 064693-0341; which is based upon and claimspriority to U.S. Provisional Application 61/366,095, filed Jul. 20,2010, entitled “High Telomerase Activity Bone Marrow Mesenchymal StemCells, Methods of Producing the Same and Pharmaceuticals and TreatmentMethods Based Thereon,” attorney docket no. 064693-0340. The entirecontent of each of these applications is incorporated herein byreference.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

This invention was made with government support under Contract No.R01DE17449 awarded by the National Institute of Dental and CraniofacialResearch/National Institute for Health. The government has certainrights in the invention.

FIELD OF THE INVENTION

The present invention relates in general to bone marrow mesenchymal stemcells, and more specifically to a subset of novel BMMSCs having hightelomerase activity, pharmaceutical compositions comprising the BMMSCs,immunomodulation methods using the BMMSCs, and treatment methods forsystemic lupus erythemetosis by administration of the BMMSCs.

BACKGROUND OF THE INVENTION

Bone marrow mesenchymal stem cells (BMMSCs) are hierarchical postnatalstem cells capable of self-renewing and differentiating intoosteoblasts, chondrocytes, adipocytes, and neural cells (Bianco et al.,2001; Friedenstein et al., 1974; Owen et al., 1988; Pittenger et al.,1999; Prockop et al., 1997).

Due to the heterogeneity of the BMMSCs, there is no single, uniquemarker allowing for BMMSC isolation, rather an array of cell moleculesare utilized to profile BMMSCs. It is widely accepted that BMMSCsexpress SH2 (CD105), SH3/SH4 (CD73), integrin β₁ (CD29), CD44, Thy-1(CD90), CD71, vascular cell adhesion molecule-1 (CD106), activatedleukocyte cell adhesion molecule (CD166), STRO-1, GD2, melanoma celladhesion molecule (CD146), Octamer-4 (Oct4), and stage-specificembryonic antigen-4 (SSEA4) (Conget et al., 1999; Galmiche et al., 1993;Gronthos et al., 2003; Haynesworth et al., 1992; Martinez et al., 2007;Pittenger et al., 1999; Sacchetti et al., 2007; Shi et al., 2003;Simmons et al., 1991; Sordi et al., 2005). It is generally believed thatBMMSCs are negative for hematopoietic cell markers such as CD14 and CD34with a very low level of telomerase activity (Conget et al., 1999; Covaset al., 2008; Galmiche et al., 1993; Haynesworth et al., 1992; Martinezet al., 2007; Pittenger et al., 1995; Sacchetti et al., 2008; Shi etal., 2002, 2003; Sordi et al., 2005). Recent studies have implied thatmouse BMMSCs might express the hematopoietic surface molecules, CD45(Chen et al., 2007) and CD34 (Copland et al., 2008).

BMMSCs are considered to be progenitors of osteoblasts with the capacityto regenerate bone and marrow components in vivo. These findings haveled to extensive studies using BMMSCs for mineralized tissueengineering. The clinical evidence appears to support the notion thatBMMSC implantation is able to improve cell-based skeletal tissueregeneration (Kwan et al., 2008; Panetta et al., 2009). Recently,evidence has accumulated that BMMSCs produce a variety of cytokines anddisplay profound immunomodulatory properties (Nauta et al., 2007;Uccelli et al., 2007, 2008), perhaps by inhibiting the proliferation andfunction of several major immune cells such as natural killer (NK)cells, dendritic cells, T and B lymphocytes (Aggarwal and Pittenger,2005; Nauta et al., 2007; Uccelli et al., 2007, 2008). These uniqueproperties make BMMSCs of great interest for clinical applications intreating immune disorders (Nauta and Fibbe, 2007; Bernardo et al.,2009).

BMMSCs are thought to be derived from bone marrow stromal compartment,initially appearing as adherent, single colony clusters (colony-formingunit-fibroblasts [CFU-F]), and subsequently proliferating on culturedishes (Friedenstein et al., 1980). Adherent BMMSCs are able toproliferate and undergo osteogenic differentiation, providing the firstevidence of CFU-F as precursors for osteoblastic lineage (Friedensteinet al., 1980). For over 40 years, the adherent CFU-F assay has been usedas an effective approach to identify and select BMMSCs. To date, theCFU-F assay has been considered to be one of the gold standards forBMMSC isolation and expansion (Clarke et al., 1989; Friedenstein et al.,1970).

SUMMARY OF THE INVENTION

Bone marrow mesenchymal stem cells (BMMSCs) are a heterogeneouspopulation of postnatal precursor cells with the capacity ofdifferentiating into multiple cell types and offering alternativetreatments for a variety of diseases. We have shown that the standardadherent CFU-F assay collects the majority of BMMSCs, but distinctsubpopulations of BMMSCs are sustained in the culture suspension.

One aspect of the present invention is directed to novel subsets ofBMMSCs with enhanced therapeutic potential.

Another aspect of the present invention is directed to methods ofcollecting and isolating the novel BMMSCs of the present invention.

Another aspect of the present invention is directed to methods forinducing the conversion of regular BMMSCs into more therapeuticallypotent BMMSCs.

Another aspect of the present invention includes isolated human bonemarrow mesenchymal stem cells having high telomerase activity. Hightelomerase activity is most broadly defined as a population of BMMSCsthat have higher telomerase activity than Regular BMMSCs, but preferablythe isolated subset of human BMMSCs has a telomerase activity of atleast two times higher than regular BMMSCs. In a preferred embodiment,at least about 6%, and more preferably at least 20% of the cells of theisolated human bone marrow mesenchymal stem cells of the invention areCD34⁺.

The isolated human bone marrow mesenchymal stem cells according to thepresent invention include: (1) isolated BMMSCs derived from non-adherentcells in the plastic culture (hereinafter referred to as “tBMMSCs”); (2)isolated CD34⁺ BMMSCs, preferably, CD34⁺/CD73⁺ BMMSCs; and (3) HumanCD34⁻ BMMSCs that have been treated with a telomerase induction agent(e.g. TAT-BMMSCs).

Another aspect of the present invention inventions is directed topharmaceutical compositions comprising the isolated human bone marrowmesenchymal stem cells according to the present invention. Additionally,the pharmaceutical composition may further comprise a carrier.

Another aspect of the present invention is directed to the separationand isolation of tBMMSCs from a heterogenous population of postnatalprecursor cells. tBMMSCs are capable of adhering to extracellular cellmatrix (ECM)-coated dishes and showing mesenchymal stem cellcharacteristics with distinction to hematopoietic cells as evidenced byco-expression of CD73 or CD105 with CD34, forming single colony clusteron ECM, and fail to differentiate into hematopoietic cell lineage.

Another aspect of the present invention is a method of convertingregular CD34⁻ BMMSCs to tBMMSCs by treating BMMSCs with telomerase,including aspirin and its related compounds with similar chemicalstructure.

Another aspect of the present invention is directed to methods ofmodulating the immune system. The methods of the present inventioninvolve administering to a patient in need thereof an effective amountof the isolated human bone marrow mesenchymal stem cells according tothe present invention.

Another aspect of the present invention is directed to treatment methodsfor systemic lupus erythematosus (SLE) via, without being limited bytheory, high levels of nitric oxide (NO) production. The treatmentmethods include administering to a patient in need thereof an effectiveamount of the isolated human bone marrow mesenchymal stem cellsaccording to the present invention. This high NO production in theisolated human bone marrow mesenchymal stem cells according to thepresent invention, for example tBMMSCs, is positively regulated bytelomerase activity coupling with the Wnt/beta-catenin signaling.Furthermore, we show that telomerase activator-induced tBMMSCs alsoexhibit significantly improved immunomodulatory function, suggesting afeasibility of inducing immuno-activated BMMSCs to improve cell-basedtherapies for immune disorders.

These and other aspects of the present invention are described withreference to the figures, description, examples, and other disclosuresas described herein.

BRIEF DESCRIPTION OF THE FIGURES

FIGS. 1A-1F show that tBMMSCs are capable of attaching on ECM-coatedculture dish. (FIG. 1A) Hypothetic model indicates that bone marrow allnuclear cells (ANCs) were seeded at 15×10⁶ into 10 cm culture dishes andincubated for 2 days in the regular culture medium at 37° C. with 5%CO2, and subsequently non-attached cells from culture suspension weretransplanted into immunocompromised mice subcutaneously usinghydroxyapatite tricalcium phosphate (HA) as a carrier for 8 weeks. Newlyformed bone (8) by osteoblasts (open arrows) and associated connectivetissue (C) were detected in this non-attached cell transplants by H&Estaining. Original magnification; X 200. Bar=100 μm. (FIG. 1B)Hypothetic model of isolating tBMMSCs. Primary ANCs were seeded at15×10⁶ into 10 cm culture dishes, BMMSCs usually attach on plasticdishes within 2 days, however, a small portion of BMMSCs in primary ANCsfailed to attach to the culture dishes and remain in the cellsuspension. The cell suspensions containing putative non-attached BMMSCswere collected and transferred to the cultured dishes coated with ECMproduced by BMMSCs with generating single colony clusters (CFU-F). TheseECM-attached BMMSCs (tBMMSCs) were sub-cultured on regular plasticculture dishes for additional experiments. (FIG. 1C) The number ofplastic attached CFU-F generated from 1.5×10⁶ whole bone marrow ANCs ismore than 7 folds high than that derived from BMMSC-ECM adherenttBMMSCs. (FIG. 1D) Flow cytometric analysis indicates that tBMMSCsexpress high levels of mesenchymal stem cell markers CD73 (81.8%), Sca-1(87.74%), Oct4 (40.7%), and SSEA4 (24.56%) compared to regular BMMSCs(CD73: 70.8%, Sca-1: 52.16%, Oct4: 14.08%). However, it appears thattBMMSCs and BMMSCs express similar level of SSEA-4. (FIG. 1E)Proliferation rates of SSEA4⁺ tBMMSCs and regular BMMSCs were assessedby BrdU incorporation assay for 24 hrs. The number of positive cells wasindicated as a percentage to the total number of each population. Thepercentage of positive cells is significantly increased in tBMMSCs whencompared to control group. (FIG. 1F) tBMMSCs exhibit a significantincrease in population doublings when compared to regular BMMSCs.

FIGS. 2A-2L show that tBMMSCs express CD34 and possess high telomeraseactivity. (FIG. 2A) Flow cytometric analysis showed that regular BMMSCsfail to express CD34, but positive for CD45 antibody staining (21.35%).However, tBMMSCs express both CD34 (23.37%) and CD45 (31.22%). (FIG. 2B)Flow cytometric analysis also showed that CD34⁺ tBMMSCs were positiveanti CD73 (13.8%) and Oct4 (13.41%) antibody staining. None staininggroups were used as negative controls. (FIGS. 2C, 2D) Western blotanalysis indicates that tBMMSCs express CD34 and mesenchymal surfacemolecules CD73 and CD105. In contrast, regular BMMSCs only express CD73and CD105 (C). tBMMSCs express CD34 at passage 1-5 (FIG. 2D). β-actinwas used as a sample loading control. BMC: whole bone marrow ANC. (FIGS.2E, 2F) Immunocytostaining confirms that tBMMSCs are double positive forCD34/CD73 (triangle, FIG. 2E) and CD34/CD105 (triangles, FIG. 2F).Regular BMMSCs are negative for CD34 antibody staining and only positivefor anti CD73 (FIG. 2E) and CD 105 (FIG. 2F) antibody staining. Bar=100μm. (FIG. 2G) tBMMSCs have significant high level of telomerase activitythan BMMSCs. HEK293T cells (293T) were used as positive control and heatinactive HEK293T cells (H.I.) were used as negative control measured bya Telo TAGGG Telomerase PCR ELISA kit. (FIG. 2H) Western blot verifiesthat tBMMSCs express telomerase reverse transcriptase (TERT) and BMMSCsare negative for anti TERT antibody staining. (FIG. 2I) There are 3.77%cells are double positive for anti CD34 and CD73 antibody staining inwhole bone marrow ANCs, these CD34⁺/CD73⁺ cells can be sorted out frombone marrow using flow cytometric sorter. (FIG. 2J) CD34⁺/CD73⁺ cellsform CFU-F on BMMSC-ECM cultures at frequency similar to tBMMSCs. (FIG.2K) CD34⁺/CD73⁺ BMMSCs show higher telomerase activity than regularBMMSCs. HEK293T cells were used as positive control (293T) and heatinactive HEK293T cells were used as negative control (H.I.) measured bya Telo TAGGG Telomerase PCR ELISA kit. (FIG. 2L) CD34⁺/CD73⁺ BMMSCs alsoshow a significant NO production when compared to regular BMMSCs. Theresults were representative of five independent experiments. Scalebars=50 μm. ***P<0.001. The graph bar represents mean±SD.

FIGS. 3A-C show that aspirin treatment elevates CD34 expression inBMMSCs. (FIG. 3A) Flow cytometric analysis indicated thataspirin-treated BMMSC (TAT-BMMSC) exhibits positive expression of CD34when compared to the negative CD34 expression in regular BMMSC (BMMSC).The expression levels of CD45 in TAT-BMMSC were lower than that inBMMSCs and tBMMSC. (FIG. 3B) TAT-BMMSCs express significant high levelsof Scal1, Oct4 and CD34 when compared to BMMSCs, but at much lower levelthan tBMMSC. However, TAT-BMMSC expresses much lower level of CD45compared to tBMMSC and regular BMMSCs. (FIG. 3C) Western blot analysisshowed that tBMMSCs and aspirin-treated BMMSCs express CD34, but BMMSCsfail to express to CD34. The results were representative of fiveindependent experiments. **P<0.01; ***P<0.005. The graph bar representsmean±SD.

FIGS. 4A-B show Hematopoietic differentiation of tBMMSCs. (FIG. 4A)BMMSCs, tBMMSCs and aspirin treated BMMSCs were cultured onto 35 mm lowattach culture dish (2×10⁴/dish) under hematopoietic differentiationmedium with or without erythropoietin (EPO; 3 U/mL) for 7 days. Wholebone marrow cells and linage negative bone marrow cells (Linage-cells)were used as positive controls. The results were representative of fiveindependent experiments. (FIG. 4B) Mice received either regular BMMSCs(BMMSC, n=5) or PBS without cells (Control, n=8) failed to survive over14 days. The whole bone marrow cell infusion group (Whole BM cells, n=3)is a positive control group with survival over 110 days afterirradiation. tBMMSCs can extend life span of lethal dose irradiated mice(tBMMSC, n=10). Kaplan-meier survival curves.

FIGS. 5A-5M show that tBMMSCs show up-regulated immunomodulatoryproperties. (FIG. 5A) NO levels in the supernatant of tBMMSC and regularBMMSC culture (each 0.2×10⁶/well on 24-well plate) were significantlyhigher in INF-γ (25 ng/ml)/IL-1β (5 ng/ml)-treated tBMMSC group than inregular BMMSCs. (FIGS. 5B-5J) Anti-CD3 and anti-CD28 (each 1 μg/ml)antibodies-activated spleen (SP) cells (1×10⁶/chamber) in the upperchambers were co-cultured with or without tBMMSCs or regular BMMSCs(1×10⁵/chamber) in the bottom chamber using a transwell system. Threedays after the co-culture, cell viability of the activated SP cells wasassayed using a cell counting kit-8 (FIGS. 5B-5D). tBMMSC-cocultureshowed a significant reduction on cell viability of activated SP cellscompared to the cells cultured without BMMSCs (BMMSC−) and with regularBMMSCs (FIG. 5B). The effects of reducing spleen cell viability bytBMMSCs, but not regular BMMSCs, were abolished in general NOS inhibitorL-NMMA (1 mM)-treated (FIG. 5C) and iNOS specific inhibitor 1400 W (0.2mM)-treated (FIG. 5D) groups. Three days after the co-culture, theactivated SP cells in the upper chamber were stained to detect apoptoticcells as described in Materials and Methods (FIGS. 5E-5J). Both tBMMSCsand regular BMMSCs were capable of inducing significant amount ofAnnexin V (+) early apoptotic cells (FIG. 5E) and Annexin V (+) 7AAD (+)late apoptotic and dead cells (FIG. 5H) compared to negative controlgroups (BMMSC−). It appeared that tBMMSCs have a significant effect thanregular BMMSC in induction of early (FIG. 5E) and late (FIG. 5H)apoptotic cells. Both L-NMMA and 1400 W were able to abolish tBMMSC andBMMSC induced Annexin V (+) (FIG. 5F, 5I) and Annexin V (+) 7AAD (+)cells (FIGS. 5G, 5J). It appeared that 1400 W treatment has moresignificant inhibition on tBMMSC-induced early apoptosis of activated SPcells (FIG. 5G). (FIG. 5K-5M) Activated CD4⁺CD25⁻ T-cells (1×10⁶/well)and tBMMSCs or regular BMMSCs (each 0.1×10⁶/well) were co-cultured inthe presence of TGFβ1 (2 ng/ml) and IL-2 (2 ng/ml) with or without NOSinhibitor for 3 days. The floating cells were stained forCD4⁺CD8⁻CD25⁺FoxP3⁺ regulatory T cells (Treg). tBMMSCs showed asignificant effect in up-regulating Foxp3⁺ regulatory T cells (Treg)(FIG. 5K). However, L-NMMA and 1400 W treatments resulted in aabolishing of tBMMSC-induced up-regulation of Treg (FIG. 5L, 5M). Theresults were representative of, at least, three independent experiments.*P<0.05; **P<0.01; ***P<0.001. The graph bar represents mean±SD.

FIGS. 6A-6I show that tBMMSCs showed superior therapeutic effect onSLE-like MRL/lpr mice. (FIG. 6A) A hypothetic model showing that tBMMSCsor regular BMMSCs from C3H/HeJ mice were infused into the tail vein of10-week-old MRL/lpr mice (0.1×10⁶ cells/10 g of mouse body weight).(FIG. 6B) tBMMSC and BMMSC treatment recover SLE-induced basal membranedisorder and mesangium cell over-growth in glomerular (G) (H&Estaining). (FIG. 6C) Urine protein levels were assessed at 2 weeks postBMMSC infusion. Both tBMMSCs and BMMSCs were capable of reducing urineprotein levels compared to MRL/lpr group. However, tBMMSCs offered amore significant reduction of urine protein levels compared to regularBMMSCs. (FIGS. 6D, 6E) ELISA quantified that levels of anti dsDNA IgGand IgM antibodies were significantly increased in the peripheral bloodof MRL/lpr mice when compared to the undetectable level (N.D.) incontrols (C3H). tBMMSC and BMMSC treatments were able to reduce levelsof anti dsDNA IgG and IgM, but tBMMSCs show superior treatment effectthan BMMSC in reducing dsDNA IgG level (FIG. 6D). (FIG. 6F) tBMMSC andBMMSC treatments were able to significantly reduce anti nuclear antibody(ANA) in MRL/lpr mice, which was significantly increased compared to thecontrol (n=6). But tBMMSC showed better effect in reducing ANA levelscompared to BMMSC treatment. (FIG. 6G) tBMMSC and BMMSC treatments wereable to increase albumin level compared to the level in MRL/lpr mice),which were significantly decreased compared to the control (n=6). tBMMSCtreatments show more effective in elevating albumin level in serum whencompared to BMMSC-treated group. (FIG. 6H) Flow cytometric analysisshowed that the number of CD25⁺Foxp3⁺ Tregs in CD4⁺ T lymphocytes ofMRL/lpr peripheral blood was reduced as compared to the control). BMMSCand tBMMSC treatments elevated the number of Tregs. It appeared thattBMMSCs induced a more significant elevation of Treg levels than BMMSCs.(FIG. 6I) Flow cytometry revealed that MRL/lpr mice had significantlyincreased level of CD4⁺IL17⁺IFNg⁻ T lymphocytes (Th17 cells) in spleencompared to control group. The Th17 cells were markedly decreased inBMMSC and tBMMSC treated groups. tBMMSC treatment induced a moresignificant reduction of Th17 cells than BMMSCs. The results wererepresentative of six independent experiments. *P<0.05; **P<0.01;***P<0.001. The graph bar represents mean±SD.

FIGS. 7A-7L show that Nitric oxide production by BMMSCs is governed bytelomerase and Wnt/beta-catenin signaling. (FIGS. 7A, 7B) tBMMSCs werecultured with telomerase inhibitor III (1 μM) for one week. Telomeraseactivity (FIG. 7A) and NO production (FIG. 7B) were significantlyreduced in telomerase inhibitor treatment group. 293T cells andheat-inactivated samples were used as positive and negative control,respectively. (FIG. 7C-7E) Regular BMMSCs were cultured with aspirin orTelomerase inhibitor III (Telo I, 1 μM) for one week. Aspirin canelevate telomerase activity (FIG. 7C), telomerase reverse transcriptase(TERT) expression (FIG. 7D) and NO production (FIG. 7E) in BMMSCs. Incontrast, Telomerase inhibitor III reduces telomerase activity (C) andNO production (FIG. 7E). (FIG. 7F) In aspirin treatment group, a Wntinhibitor, DKK1 (DKK, 10 ng/ml), was added to the BMMSC cultures forthree days (DKK-TAT), which led to a significantly reduction of NOlevels compared to aspirin (TAT) group. (FIG. 7G) Western blot analysisshowed that DKK1 can reduce active β-catenin levels. Aspirin (TAT)treatment can partially block DKK1-induced down-regulation of activatedbeta-catenin expression. (FIG. 7H) DKK1 treatment was able to abolishaspirin (TAT)-induced telomerase activity in BMMSCs (DKK-TAT). (FIG. 7I)When BMMSCs were cultured with Chiron, activator of beta cateninsignaling, at 1 and 10 μM for 1 week. NO production in BMMSCs wassignificantly increased in a dose dependent manner as measured by TotalNO/Nitrite/Nitrate kit. (FIG. 7J) Western blot analysis confirmed thatChiron treatment induces up-regulated expression of active beta-cateninin BMMSCs. (FIG. 7K) Chiron treatment is able to induce a hightelomerase activity, which is blocked by telomerase inhibitor III (Teloi-Chiron) when used prior to the Chiron induction. 293T cell and heatinactivated sample were used as positive and negative controlrespectively. (FIG. 7L) Chiron induced high NO production can be blockedby telomerase inhibitor III treatment. The results were representativeof five independent experiments. *P<0.05; **P<0.01; ***P<0.001. Thegraph bar represents mean±SD.

FIGS. 8A-8G show that aspirin-treated BMMSCs showed improved therapeuticeffect on SLE-like MRL/lpr mice. (FIG. 8A) Urine protein levels wereassessed at 2 weeks post BMMSC infusion. Both BMMSCs and aspirin (TAT)treated BMMSCs (TAT-BMMSC) were capable of reducing urine protein levelscompared to MRL/lpr group. However, TAT-BMMSC offered a more significantreduction of urine protein levels compared to regular BMMSCs when0.1×10⁶ or 0.01×10⁶ cells were systemically infused. It appeared that0.01×10⁶ BMMSCs failed to reduce urine protein level compared to MRL/lprmice. (FIGS. 8B, 8C) ELISA quantified that levels of anti dsDNA IgG andIgM antibodies were significantly increased in the peripheral blood ofMRL/lpr mice when compared to the controls (C3H). TAT-BMMSC and BMMSCtreatments were able to reduce levels of anti dsDNA IgG and IgM, butTAT-BMMSC show superior treatment effect than BMMSC in reducing dsDNAIgG and IgM levels. TAT-BMMSC of 0.01×10⁶ cell infusion group was ableto significantly reduce the levels of anti dsDNA IgG and IgM. (FIG. 8D)TAT-BMMSC and BMMSC treatments were able to significantly reduce antinuclear antibody (ANA) in MRL/lpr mice, which was significantlyincreased compared to the control (C3H). But TAT-BMMSC of 0.01×10⁶ cellinfusion group showed better effect in reducing ANA levels compared toBMMSC treatment. (FIG. 8E) ELISA analysis showed that TAT-BMMSC andBMMSC treatments were able to reduce serum IL17 levels compared to thehigh level in MRL/lpr mice. However, TAT-BMMSC of 0.01×10⁶ cell infusiongroup showed more effective in reducing IL17 level in serum whencompared to BMMSC-treated group. (FIG. 8F) Flow cytometry revealed thatMRL/lpr mice had significantly increased level of CD4⁺IL17⁺IFNg⁻ Tlymphocytes (Th17 cells) in spleen compared to control group (C3H). TheTh17 cells were markedly decreased in TAT-BMMSC and BMMSC treatedgroups. TAT-BMMSC treatment induced a more significant reduction of Th17cells than BMMSC groups. (FIG. 8G) Flow cytometric analysis showed thatthe number of CD25⁺Foxp3⁺Tregs in CD4⁺T lymphocytes of MRL/lprperipheral blood was reduced as compared to the control (C3H). TAT-BMMSCand BMMSC treatments elevated the number of Tregs. It appeared thatTAT-BMMSCs induced a more significant elevation of Treg levels thanBMMSCs when 0.01×10⁶ cells were systemically infused. The results wererepresentative of six independent experiments. *P<0.05; **P<0.01;***P<0.001. The graph bar represents mean±SD.

FIGS. 9A-9E show that human bone marrow contains tBMMSCs. (FIG. 9A)human tBMMSCs (htBMMSC) showed significantly high level telomeraseactivity than BMMSCs (hBMMSC) as measured by Telo TAGGG Telomerase PCRELISA kit. 293T cells and heat inactive (H.I.) were used as positive andnegative controls, respectively. (FIG. 9B) htBMMSCs produce high levelof NO than that of hBMMSCs as assessed by Total NO/Nitrite/Nitrate kit.(FIG. 9C) Kynurenine production was significantly increased in htBMMSCcompare to hBMMSC (p<0.005). (FIG. 9D) When hBMMSC or htBMMSC wereco-cultured with active T cell, the kynurenine level in co-culturesystem was dramatically increased with more significantly increase inhtBMMSC group compare to hBMMSC group. (FIG. 9E) Annexin V and 7AADdouble positive apoptotic cell numbers in active T cells were increasedwhen co-cultured with hBMMSC or htBMMSC. However, apoptotic cell ratewas significantly increased in htBMMSC group compared to hBMMSC group.The results were representative of three independent experiments.*P<0.05; **P<0.01; ***p<0.005. The graph bar represents mean±SD.

FIG. 10 shows the number of CFU-F in BMMSC cultures. Primary ANCs wereseeded at 1×106 into 6 cm normal plastic culture dishes (Plastic) or theculture dishes coated with ECM produced by BMMSCs (ECM) for 14 days. TheCFU-F number was significantly increased in BMMSCs cultured in ECMcoated dishes. The results were representative of five independentexperiments. ***P<0.001. The graph bar represents mean±SD.

FIGS. 11A-11D show the multipotent differentiation of tBMMSCs. (FIG.11A) Alizarin Red S and alkaline phosphatase (ALP) staining showed thattBMMSCs were similar to regular BMMSCs in osteogenic differentiation invitro. (FIG. 11B) tBMMSCs or regular BMMSCs (4×106 cells/transplant)were transplanted into immunocompromised mice using HA/TCP (HA) as acarrier for 8 weeks. Bone formation was detected in tBMMSC and BMMSCtransplants, evidenced by H&E staining. HA; hydroxyapatite tricalciumphosphate, B; bone, M; bone marrow, C; connective tissue; Originalmagnification; X 200. Bar=50 μm. (FIG. 11C) tBMMSCs are capable offorming Oil Red 0 positive cells and expression of PPARγ2 and LPL mRNAas seen in regular BMMSCs by Oil Red 0 staining and RT-PCR analysis,respectively. Glyceraldehyde 3-phosphate dehydrogenase (GAPDH) was usedas an internal control. The results were representative of fiveindependent experiments. Scale bars=100 μm. 1: negative control, 2:BMMSC, 3: tBMMSC. (FIG. 11D) Chondrogenic differentiation was assessedby Alcian blue staining for acidic sulfated mucosubstances, Pollak'sTrichrome staining for collagen, and immunohystochemical staining forcollagen type II. tBMMSCs were able to differentiate into chondrocytesas observed in regular BMMSCs. Bar=50 μm. The results wererepresentative of three independent experiments. The graph barrepresents mean±SD.

FIGS. 12A-12B show the NO level in tBMMSCs. BMMSCs and tBMMSCs(2×105/well) were cultured for 3 days and treated with L-NMMA (1 mM) or1400 W (0.2 mM) for 3 days. (FIG. 12A) The collected culture supernatantwas used to measure NO level. The results were representative of fiveindependent experiments. (FIG. 12B) Western blot analysis showed thatiNOS expression was inhibited by LNMMA and 1400 W. *P<0.05; ***P<0.001.The graph bar represents mean±SD.

FIGS. 13A-13C show the osteoclast activity in tBMMSC-treated MRL/lprmice. (FIG. 13A) TRAP staining indicated the increased number of TRAPpositive cells in epiphysis of the distal femurs of MRL/lpr mice ascompared to the control (C3H). tBMMSC and BMMSC infusion resulted in asignificant reduced number of TRAP positive cells. It appears thattBMMSC group shows more significant reduction of number of TRAP positivecells than BMMSC group. (FIGS. 13B, 13C) ELISA revealed that MRL/lprmice have increased levels of soluble RANKL (sRANKL) (FIG. 13B) andC-terminal telopeptides of type I collagen (CTX) (FIG. 13C) in serum ascompared to the controls. tBMMSC and BMMSC infusion can significantlyreduce levels of sRANKL (FIG. 13B) and CTX (FIG. 13C), but tBMMSC groupshowed a more effective in reduce levels of sRANKL (FIG. 13B) and CTX(FIG. 13C). The results were representative of five independentexperiments. *P<0.05; **P<0.01; ***P<0.001. The graph bar representsmean±SD.

FIGS. 14A-14C show that the immunomodulatory properties of BMMSCs areregulated by telomerase. SP cells (1×106/chamber), activated with antiCD3 (5 μg/mL) and CD28 (2 μg/mL) antibodies, were co-cultured with orwithout BMMSCs (0.2×106/chamber) using a Trans-well system (Corning) for3 days. BMMSCs were treated with TAT analog (TAT, 3 μM) for 3 days priorto the co-culture. Cell viability of SP cells was measured using a cellcounting kit-8 (Dojindo Molecular Technoloies, Gaithersburg, Md.).Apoptotic cells were stained with Annexin V-PE apoptosis detection kit I(BD Bioscience) and analyzed with FACSCalibur (BD Bioscience). TATanalog-treated BMMSCs (TAT-BMMSC) could significantly reduce activatedSP cell viability (FIG. 14A) and enhance early (FIG. 14B) and late (FIG.14C) apoptosis of activated SP cells compared to regular BMMSCs. Theresults were representative of five independent experiments. *P<0.05;**P<0.01; ***P<0.001. The graph bar represents mean±SD.

DETAILED DESCRIPTION OF THE INVENTION Abbreviations

BMMSCs: bone marrow mesenchymal stem cells;

CFU-F: colony-forming units fibroblastic;

ECM: extracellular cell matrix;

Oct4: Octamer-4;

SSEA4: stage specific embryonic antigen-4;

SLE: systemic lupus erythematosus;

HA/TCP: hydroxyapatite tricalcium phosphate;

Tregs: CD4+CD25+Foxp3+regulatory T cells;

ANCs: all nuclear cells

DEFINITIONS

Unless otherwise indicated herein, all terms used herein have themeanings that the terms would have to those skilled in the art of thepresent invention. Practitioners are particularly directed to currenttextbooks for definitions and terms of the art. It is to be understood,however, that this invention is not limited to the particularmethodology, protocols, and reagents described, as these may vary.

Individual cells and cell populations will be referred to herein by useof a ‘+’ or a ‘−’ symbol to indicate whether a certain cell or cellpopulation expresses or lacks a specific marker, e.g. a CD molecule.When used in connection with a single cell, the use of a ‘+’ or a ‘−’symbol indicates whether that cell expresses or lacks the specificmarker. For example, a “CD34+”, CD31−” cell is one that expresses CD34,but not CD31. When used in connection with cell populations, the use ofa ‘+’ or a ‘−’ symbol to indicate whether a certain cell population, ora portion thereof, expresses or lacks the specific marker.

As used herein, so-called “regular BMMSCs” are BMMSCs appearing asadherent, single colony clusters (colony-forming unit-fibroblasts[CFU-F]) on regular plastic culture, and subsequently proliferating onculture dishes (Friedenstein et al., 1980).

“Treatment” refers to both therapeutic treatment and prophylactic orpreventative measures, wherein the object is to prevent or slow down(lessen) the targeted pathologic condition or disorder. Those in need oftreatment include those already with the disorder as well as those proneto have the disorder or those in whom the disorder is to be prevented.

An “therapeutically effective amount” of tBMMCs is an amount sufficientto carry out a specifically stated purpose. An “effective amount” may bedetermined empirically and in a routine manner in relation to the statedpurpose.

A “Carrier” or “Carriers” as used herein include pharmaceuticallyacceptable carriers, excipients, or stabilizers which are nontoxic tothe cell or mammal being exposed thereto at the dosages andconcentrations employed. The physiologically acceptable carrier may be asterile aqueous pH buffered solution. Examples of physiologicallyacceptable carriers include buffers such as phosphate, citrate, andother organic acids; antioxidants including ascorbic acid; low molecularweight (less than about 10 residues) polypeptide; proteins, such asserum albumin, gelatin, or immunoglobulins; hydrophilic polymers such aspolyvinylpyrrolidone; amino acids such as glycine, glutamine,asparagine, arginine or lysine; monosaccharides, disaccharides, andother carbohydrates including glucose, mannose, or dextrins; chelatingagents such as EDTA; sugar alcohols such as mannitol or sorbitol;salt-forming counterions such as sodium; and/or nonionic surfactants.

One aspect of the present invention is directed to unique subsets ofisolated human bone marrow mesenchymal stem cells having high telomeraseactivity. High telomerase activity is most broadly defined as apopulation of BMMSCs that have higher telomerase activity than RegularBMMSCs, but preferably the isolated subset of human BMMSCs has atelomerase activity of at least two times higher than regular BMMSCs.Isolated human BMMSCs having high telomerase activity according to thepresent invention are generally characterized by having an increasedexpression of CD34 relative to regular BMMSCs. Preferably, at leastabout 6%, and more preferably at least 20% of the cells of the isolatedhuman bone marrow mesenchymal stem cells of the invention are CD34⁺. Inits broadest sense, the term “isolated” when used in connection with apopulation of cells of interest, means that the population of cells isat least partially isolated from other cell types or other cellularmaterial with which it naturally occurs in the tissue of origin (e.g.,bone marrow). In another embodiment, the isolated stem cells also aresubstantially free of soluble, naturally occurring molecules.

The isolated human bone marrow mesenchymal stem cells according to thepresent invention include: (1) isolated human BMMSCs derived fromnon-adherent cells in the plastic culture (hereinafter referred to as“tBMMSCs”); (2) isolated CD34⁺ BMMSCs, preferably, CD34⁺/CD73⁺ BMMSCs;and (3) Human CD34⁻ BMMSCs that have been treated with a telomeraseinduction agent (e.g. TAT-BMMSCs). Unless otherwise specifically stated,all BMMSCs in the present invention are human BMMSCs.

The human bone marrow useable in connection with the present inventionmay generally be obtained from within human bone. Preferably, the bonemarrow is postnatal bone marrow. All nucleated cells of the bone marroware typically used. Most preferably, bone marrow derived all nuclearcells (ANCs) from femurs and tibias are used as described herein.

Specific cell types described and identified herein may be isolated fromcollected cells employing techniques known by those skilled in the art,such as for example, but not limited to density gradient centrifugation,magnet cell separation, flow cytometry, affinity cell separation ordifferential adhesion techniques. In a preferred embodiment, the stemcells of the present invention can be purified by, for example, flowcytometry (e.g., FACS analysis), as discussed below. The high telomeraseBMMSCs described herein will undergo ex vivo expansion according toknown methods for BMMSCs to enrich cell numbers for tissue regenerationor systemic therapies.

Isolated tBMMSCS

tBMMSCs are generally isolated from a heterogenous population ofpostnatal precursor cells. Isolated tBMMSCs are generally characterizedas human BMMSCs that fail to form single colony clusters (CFU-F) inplastic cultures but are capable of adhering on mesenchymal stemcell-produced ECM and exhibit increased expression of telomeraserelative to regular human BMMSCs. tBMMSCs show mesenchymal stem cellcharacteristics with distinction to hematopoietic cells as evidenced byco-expression of CD73 or CD105 with CD34. tBMMSCs fail to differentiateinto hematopoietic cell lineage.

Another aspect of the present invention is directed to a method ofisolating tBMMSCs comprising: culturing a sample of bone marrow derivedall nuclear cells on a plastic substrate; removing cells that do notadhere to the plastic substrate; culturing the removed cells on aBMMSC-ECM coated medium; and collecting colonies forming attached cellson the BMMSC-ECM medium.

More specifically, tBMMSCs may be produced and isolated as follows:Primary ANCs are seeded on plastic substrate, for example plasticculture dishes. tBMMSCs in primary ANCs fail to attach to the culturedishes and remain in the cell suspension. The cell suspensionscontaining putative non-attached tBMMSCs are collected and transferredto cultured dishes coated with Extracellular matrix (ECM) produced byBMMSCs, resulting in the generation of single colony clusters (CFU-F).These ECM-attached BMMSCs (tBMMSCs) are sub-cultured according to knownmethods on regular plastic culture. Typical flow cytometric analysisindicates that tBMMSCs express high levels of mesenchymal stem cellmarkers CD73 (e.g. about 80%), Sca-1 (e.g. about 90%), and Oct4 (e.g.about 40%) compared to regular BMMSCs (CD73: e.g. about 70%, Sca-1:about 50%, Oct4: about 14%). However, it appears that tBMMSCs and BMMSCsexpress similar level of SSEA-4.

tBMMSCs express CD34 and possess high telomerase activity relative toregular BMMSCs. As described herein, regular BMMSCs fail to expressCD34, but are positive for CD45 (about 20%). However, tBMMSCs expressboth CD34 (about 25%) and CD45 (about 30%). Western blot analysisindicates that tBMMSCs express CD34 and mesenchymal surface moleculesCD73 and CD105. In contrast, regular BMMSCs only express CD73 and CD105.tBMMSCs also have significantly higher levels of telomerase activitythan regular BMMSCs.

To ensure purity of tBMMSCs, it is preferred to isolate andsubstantially purify tBMMSCs that express a marker known to be expressedin regular BMMSCs selected from the group consisting of STRO-1, CD29,CD73, CD90, CD105, CD146, Octamer-4 (Oct4), and stage-specific embryonicantigen-4 (SSEA4). In a preferred embodiment, SSEA4⁺ tBMMSCs may beisolated and purified by techniques generally known to those of ordinaryskill, such as immune FACS. A sample of tBMMSCs stem cells is“substantially pure” when it is at least 80%, or at least 90%, or atleast 95%, and, in certain cases, at least 99% free of cells other thancells of interest. Thus, for example, a sample of SSEA4⁺ tBMMSCs stemcells is “substantially pure” when it is at least 80%, or at least 90%,or at least 95%, and, in certain cases, at least 99% free of cells otherthan SSEA4⁺ tBMMSCs. Purity can be measured by any appropriate method,for example, by fluorescence-activated cell sorting (FACS), or otherassays which distinguish cell types.

Isolated CD34⁺ Human BMMSCs

CD34⁺ BMMSCs are distinct from regular BMMSCs in terms of havingelevated telomerase activity and high levels of the earlier mesenchymalstem cell marker, Oct4, along with increased immunomodulatory function.The mechanism that may contribute to the up-regulated immunomodulatoryfunction is associated with high NO production in tBMMSCs (Ren et al.,2008) and NO-driven high Treg level (Niedbala et al., 2007), whichappears to be governed by telomerase activity coupled withWnt/beta-catenin signaling. Without being limited to theory, this isbelieved to be the reason that tBMMSCs have a superior therapeuticeffect in treating SLE mice.

Isolated CD34⁺ BMMSCs fail to form CFU-F in plastic cultures but arecapable of adhering on mesenchymal stem cell-produced ECM anddifferentiating into osteoblasts, adipocytes, and chondrocytes from bothC3H/HeJ and C57BL/6J mice. CD34⁺ BMMSCs coexpress mesenchymal stem cellmarkers CD73 and CD105. Furthermore, CD34⁺ BMMSCs are distinct from HSCdue to the fact that they are not able to differentiate intohematopoietic cell lineage in vitro and fail to rescue lethal doseirradiated mice.

Preferably, the isolated human BMMSCs are double positive for CD34 andat least one other marker known to be expressed in regular BMMSCsselected from the group consisting of STRO-1, CD29, CD73, CD90, CD105,CD146, Octamer-4 (Oct4), and stage-specific embryonic antigen-4 (SSEA4).Preferably, the BMMSCs are both CD34⁺ and CD73⁺. Preferably, IsolatedCD34⁺ BMMSCs are substantially pure. A sample of CD34⁺BMMSCs is“substantially pure” when it is at least 80%, or at least 90%, or atleast 95%, and, in certain cases, at least 99% free of cells other thancells of interest. Thus, for example, a sample (population) of CD34⁺BMMSCs is “substantially pure” when it is at least 80%, or at least 90%,or at least 95%, and, in certain cases, at least 99% free of cells otherthan CD34⁺ BMMSCs. Purity can be measured by any appropriate method, forexample, by fluorescence-activated cell sorting (FACS), or other assayswhich distinguish cell types.

As described herein, about 4% of human BMMSC's cells are double positivefor CD34 and CD73 in whole bone marrow ANCs. These CD34⁺/CD73⁺ cells canbe sorted out and isolated from bone marrow using conventionaltechniques, such as a flow cytometric sorter. The use of flow cytometryto isolate CD34⁺/CD73⁺ BMMSCs from whole bone marrow offers a practicalapproach to isolate and collect tBMMSC for clinical therapeutic use.CD34⁺/CD73⁺ cells can be sorted out and isolated from tBMMSCs and fromregular BMMSCs that have been treated with a telomerase induction agentas described herein. Preferably, the CD34⁺/CD73⁺ BMMSCs are“substantially pure.” A group of CD34⁺/CD73⁺ BMMSCs are “substantiallypure” when it is at least 80%, or at least 90%, or at least 95%, and, incertain cases, at least 99% free of cells other than CD34⁺/CD73⁺ BMMSCs.

CD34⁺/CD73⁺ cells form CFU-F on BMMSC-ECM cultures at frequency similarto tBMMSCs. CD34⁺/CD73⁺ BMMSCs also show higher telomerase activity thanregular BMMSCs. CD34⁺/CD73⁺ BMMSCs also show a significant increase inNO production compared to regular BMMSCs.

CD34 BMMSCs Treated with a Telomerase Induction Agent.

Another aspect of the present invention directed to a method ofincreasing telomerase activity in CD34⁻ human bone marrow mesenchymalstem cells comprising: contacting human bone marrow messenchymal stemcells with an effective amount of a telomerase inducing agent. The CD34−BMMSCs may, for example, be regular BMMSCs. As defined herein, a groupof BMMSCs is CD34⁻ if less than about 1% of the group is CD34⁺.

The telomerase activity of the CD34⁻ BMMSCs can be increased by addingan effective amount of telomerase induction agent to the culture medium.One preferred telomerase induction agent is aspirin, but structural andfunctional analogues of aspirin may be substituted. The cultureconditions may be appropriately determined by those of ordinary skill bymeasurement of the telomerase activity levels as described herein. Whenaspirin is used, it is preferably added into culture medium at about 2μg/ml to about 50 μg/ml for about 1 week. Culture under these conditionsresults in significantly increased level of telomerase activity inBMMSCs was achieved.

In one specific embodiment, regular human BMMSC are treated with atelomerase induction agent to become BMMSCs having high telomeraseactivity with improved immunomodulatory function. Specifically, whenaspirin is added into culture medium at 2.5 μg/ml or 50 μg/ml for 1week, significantly increased level of telomerase activity in BMMSCs wasachieved. The resulting BMMSCs are referred to herein as TAT-BMMSCs.TAT-BMMSCs exhibits positive expression of CD34 when compared to thenegative CD34 expression in regular BMMSCs. The expression levels ofCD45 in TAT-BMMSC were lower than that in BMMSCs and tBMMSC. TAT-BMMSCsexpress significant high levels of Scal1, Oct4 and CD34 when compared toBMMSCs, but at much lower level than tBMMSC. However, TAT-BMMSCexpresses much lower level of CD45 compared to tBMMSC and regularBMMSCs. Western blot analysis showed that tBMMSCs and aspirin-treatedBMMSCs express CD34, but BMMSCs fail to express to CD34.

Therapeutic Applications of High Telomerase Activity BMMSCS

Another aspect of the present invention is directed to using the BMMSCsof the present invention in the treatment of one or more disorders.

Another aspect of the present inventions is directed to a method ofimmunomodulation comprising administering to a patient in need thereof atherapeutically effective amount of isolated human bone marrowmesenchymal stem cells of the present invention.

Another aspect of the present invention is directed to a method ofincreasing the NO concentration in vivo, comprising administering to apatient in need thereof a therapeutically effective amount of theisolated human bone marrow mesenchymal stem cells of the presentinvention. NO is a gaseous biological mediator with important roles inaffecting macrophage and T cell function (Sato et al., 2007; Bogdan etal., 2001). iNOS is induced by IFNγ, TNFα, IL-1α, or IL-1β in BMMSCs,and iNOS^(−/−) mice show a reduced ability to suppress T cell functions(Ren et al., 2008). It has been reported that active endothelial NOSalong with estrogen receptor cooperatively regulates human telomeraserevere transcriptase (hTERT) expression in the endothelium (Grasselli etal., 2008). We describe herein the functional role of high telomeraseactivity in improving immunomodulatory activity of BMMSCs via elevationof approximately 10 μM NO production and approximately 5% up-regulationof Treg. Telomerase-enhanced NO production is also associated withWnt/β-catenin signaling, in which Wnt inhibitor DKK1 can blocktelomerase activator-induced telomerase activity and the associated NOproduction in BMMSCs. Furthermore, Wnt activator Chiron is able topromote telomerase activity and NO production in BMMSCs. Pre-treatmentwith telomerase inhibitor can partially abolish Wnt-activator-inducedtelomerase activity. These data suggest that telomerase coupled withWnt/beta-catenin signaling to promote NO production. Therefore, inaddition to the functional role in participating in the Wnt/beta-cateninsignaling pathway (Park et al., 2009), telomerase also collaborates withWnt/beta-catenin signaling to modulate NO production. Both telomeraseand Wnt/beta-catenin activators can induce a high NO production inregular BMMSCs leading to an improved reduction of activated SP cellviability. But only telomerase activator treatment is capable ofenhancing apoptosis of activated SP cells. It is possible that otherimmunomodulatory factors may also contribute to elevatedimmunomodulation of tBMMSC.

Another aspect of the present invention is directed to the treatment ofsystemic lupus erythematosus comprising administering to a patient inneed thereof a therapeutically effective amount of the isolated humanbone marrow mesenchymal stem cells of the present invention.

As used herein, the term an “effective amount” of the BMMSCs of thepresent invention, when used in connection with a method, is an amountof the BMMSCs sufficient to carry out a specifically stated purpose. Ingeneral, an “effective amount” in reference to treatment of a disease ordisorder may be determined empirically by reference to the data andstandards disclosed herein and in a routine manner in relation to thestated purpose. An effective amount is preferably given in a single doseto the patient; however, the effective amount may be delivered to thepatient as a number of doses over a period of time. As describe herein,the dosage of 0.1×10⁶ cells/10 g body weight are sufficient to treat SLEmice in case of regular BMMSC. By using high telomerase activity BMMSCs,the dosage can be reduced to 0.01×10⁶ cells/10 g body weight withtherapeutic effect. Those of ordinary skill can apply this to treatmentof humans using known models relating mouse to human dosages and usingknown techniques for optimization of dosages.

The present invention further includes a pharmaceutical compositioncomprising an effective amount of pharmaceutical composition comprisingisolated bone marrow mesenchymal stem cells having high telomeraseactivity in a carrier medium. The pharmaceutical compositions of thepresent invention are used for administration of the isolated bonemarrow mesenchymal stem cells having high telomerase activity fortreatment in accordance with any of the methods described herein.

In the methods described herein, the BMMSCs of the present inventionshould be compatible with the patient and be administered in atherapeutically effective amount of the BMMSCs. The therapeuticallyeffective amount can range from the maximum number of cells that issafely received by the patient to the minimum number of cells necessaryfor to achieve the intended effect. One of ordinary skill in the art candetermine and optimize effective amounts according to known techniquesto effectuate the intended purpose of the treatment.

The therapeutically effective amount of the BMMSCs can be suspended in apharmaceutically acceptable carrier. Such a carrier may include but isnot limited to a suitable culture medium plus 1% serum albumin, saline,buffered saline, dextrose, water, and combinations thereof. Theformulation should suit the mode of administration.

In a preferred embodiment, the BMMSC preparation or composition isformulated for systemic administration to human beings in accordancewith procedures for pharmaceutical formulations knows to those ofordinary skill. Typically, compositions for systemic administration aresolutions in sterile isotonic aqueous buffer. The ingredients may besupplied either separately or mixed together in unit dosage form, forexample, as a cryopreserved concentrate in a hermetically sealedcontainer such as an ampoule indicating the quantity of active agent.

A variety of means for administering cells to subjects will, in view ofthis specification, be apparent to those of skill in the art. Suchmethods include may include systemic administration or injection of thecells into a target site in a subject. Cells may be inserted into adelivery device which facilitates introduction by injection orimplantation into the subjects. Such delivery devices may include tubes,e.g., catheters, for injecting cells and fluids into the body of arecipient subject. In a preferred embodiment, the tubes additionallyhave a needle, e.g., a syringe, through which the cells of the inventioncan be introduced into the subject at a desired location. The cells maybe prepared for delivery in a variety of different forms. For example,the cells may be suspended in a solution or gel. Cells may be mixed witha pharmaceutically acceptable carrier or diluent in which the cells ofthe invention remain viable. Pharmaceutically acceptable carriers anddiluents include saline, aqueous buffer solutions, solvents and/ordispersion media. The use of such carriers and diluents is well known inthe art. The solution is preferably sterile and fluid, and will often beisotonic. Preferably, the solution is stable under the conditions ofmanufacture and storage and preserved against the contaminating actionof microorganisms such as bacteria and fungi through the use of, forexample, parabens, chlorobutanol, phenol, ascorbic acid, thimerosal, andthe like.

Modes of administration of the isolated human BMMSCs include but are notlimited to systemic intravenous or intra-arterial injection andinjection directly into the tissue at the intended site of activity. Thepreparation can be administered by any convenient route, for example byinfusion or bolus injection and can be administered together with otherbiologically active agents. Administration is preferably systemic. Itmay be advantageous, under certain conditions, to use a site ofadministration close to or nearest the intended site of activity. Whenthe composition is to be administered by infusion, it can be dispensedwith an infusion bottle containing sterile pharmaceutical grade water orsaline. Where the composition is administered by injection, an ampouleof sterile water for injection or saline can be provided so that theingredients may be mixed prior to administration.

Administration of the BMMSCs of this invention may be done incombination with one or more further therapeutic agents includingsimultaneous (concurrent) and consecutive administration in any order.

EXAMPLES

The following examples are provided in order to demonstrate and furtherillustrate certain embodiments and aspects of the present invention andare not to be construed as limiting the scope thereof. While suchexamples are typical of those that might be used, other procedures knownto those skilled in the art may alternatively be utilized. Indeed, thoseof ordinary skill in the art can readily envision and produce furtherembodiments, based on the teachings herein, without undueexperimentation.

Experimental Methods

Animals.

Female C3H/HeJ, C57BL/6J, and C3MRL-Fas^(lpr)/J mice were purchased fromJackson Lab. Female immunocompromised mice (Beige nude/nude XIDIII) werepurchased from Harlan. All animal experiments were performed under theinstitutionally approved protocols for the use of animal research (USC#10874 and 10941).

Antibodies.

Anti Oct4, SSEA4, active β catenin and β catenin were purchased fromMillipore. Anti Sca-1-PE, CD34-PE, CD34-FITC, CD45-PE, CD73-PE,CD4-PerCP, CD8-FITC, CD25-APC, CD3ε and CD28 antibodies were purchasedfrom BD Bioscience. Anti CD105-PE, Foxp3-PE, IL17-PE, and IFNγ-APCantibodies were purchased from eBioscience. Unconjugated anti CD34,CD73, and CD105, and anti TERT were purchased from Santa CruzBiosciences. Anti β actin antibody was purchased from Sigma.

Isolation of Mouse Bone Marrow Mesenchymal Stem Cells (BMMSCs).

The single suspension of bone marrow derived all nuclear cells (ANCs)from femurs and tibias were seeded at 15×10⁶ into 100 mm culture dishes(Corning) under 37° C. at 5% CO2 condition. Non-adherent cells wereremoved after 48 hours and attached cells were maintained for 16 days inalpha minimum essential medium (α-MEM, Invitrogen) supplemented with 20%fetal bovine serum (FBS, Equitech-bio), 2 mM L-glutamine, 55 μM2-mercaptoethanol, 100 U/ml penicillin, and 100 μg/ml streptomycin(Invitrogen). Colonies-forming attached cells were passed once forfurther experimental use.

Preparation of Extracellular Matrix (ECM) Coated Dishes.

ECM coated dishes were prepared as described in Chen et al. (2007).Briefly, 100% confluence of BMMSCs was cultured in culture medium with100 nM L-ascorbic acid phosphate (Wako Pure Chemical). After 2 weeks,cultures were washed with PBS and incubated with 0.005% Triton X-100(Sigma) for 5-10 min at room temperature to remove cells. The ECM wastreated with DNase 1 (100 units/ml; Sigma) for 1 h at 37° C. The ECM waswashed with PBS three times and stored in 2 ml of PBS containing 100U/ml penicillin, 100 μg/ml streptomycin, and 0.25 μg/ml fungizone(Invitrogen) at 4° C.

Isolation of tBMMSCs.

Bone marrow-derived ANCs were seeded at 15×10⁶ into 100 mm culturedishes and cultured for 48 hrs. The culture supernatant were collectedand centrifuged to obtain putative non-attached BMMSCs. The cells werere-seeded at indicated numbers on ECM-coated dishes. After 48 hrs, thefloating cells in the cultures were removed with PBS and the attachedcells on ECM were maintained for additional 14 days. Colonies-formingattached cells were passed once and sub-cultured on regular plasticculture dishes for further experiments. For some stem cellcharacterization analysis, we collected SSEA4 positive tBMMSCs usingFACS^(Calibur) flow cytometer (BD Bioscience) and expanded in thecultures.

Colony Forming Unit-Fibroblastic (CFU-F) Assay.

One million cells of ANCs from bone marrow were seeded on T25 cellculture flask (Nunc). After 16 days, the cultures were washed by PBS andstained with 1% toluidine blue solution in 2% paraformaldehyde (PFA).The cell cluster that has more than 50 cells was counted as a colonyunder microscopy. The colony number was counted in five independentsamples per each experimental group.

Cell Proliferation Assay.

The proliferation of BMMSC and tBMMSC was performed by bromodeoxyuridine(BrdU) incorporation assay. Each cell population (1×10⁴ cells/well) wereseeded on 2-well chamber slides (Nunc) and cultured for 3 days. Thecultures were incubated with BrdU solution (1:100) (Invitrogen) for 20hours, and stained with a BrdU staining kit (Invitrogen). BrdU-positiveand total cell numbers were counted in ten images per subject. The BrdUassay was repeated in 5 independent samples for each experimental group.

Population Doubling Assay.

0.5×10⁶ cells of BMMSCs and pBMMSCs were seeded on 60 mm culture dishesat the first passage. Upon reaching confluence, the cells were passagedat the same cell density. The population doubling was calculated atevery passage according to the equation: log₂ (number of harvestedcells/number of seeded cells). The finite population doublings weredetermined by cumulative addition of total numbers generated from eachpassage until the cells ceased dividing.

Flow Cytometric Analysis of Mesenchymal Stem Cell Surface Molecules.

BMMSCs or pBMMSCs (0.2×10⁶) were incubated with 1 μg of PE conjugatedantibodies or isotype-matched control IgGs (Southern Biotech) at 4° C.for 45 min. Samples were analyzed by FACS^(Calibur) flow cytometer (BDBioscience). For dual color analysis, the cells were treated with PEconjugated and FITC conjugated antibodies or isotype-matched controlIgGs (each 1 □g). The cells were analyzed on FACS^(Calibur) (BDBioscience).

Immunofluorescent Microscopy.

The cells subcultured on 8-well chamber slides (Nunc) (2×10³/well) werefixed with 4% PFA. The samples were incubated with the specific orisotype-matched mouse antibodies (1:200) overnight at 4° C., and treatedwith Rhodamine-conjugated secondary antibodies (1:300, JacksonImmunoResearch; Southern Biotechnology). Finally, they were mounted byVectashield mounting medium containing 4′,6-diamidino-2-phenylindole(DAPI) (Vector Laboratories).

Isolation of CD34⁺CD73⁺ Double Positive Cells.

Bone marrow derived ANCs were stained with anti CD34-FITC and antiCD73-PE antibodies for 30 min on ice under dark condition. After washwith PBS, cells were re-suspended into OPTI-MEM (Invitrogen) supplementwith 2% FBS and antibiotics (100 U/ml penicillin and 100 μg/mlstreptomycin) and sorted by MOFLO XDP Cell Sorter (BECKMAN Coulter). Thesorted double positive cells were seeded on ECM coated 60 mm dish atdensity of 1×10⁶/dish and cultured for further experiments.

In Vivo Bone Formation Assay.

4.0×10⁶ of cells were mixed with hydroxyapatite/tricalcium phosphate(HA/TCP) ceramic powders (40 mg, Zimmer Inc.) and subcutaneouslytransplanted into 8 weeks old immunocompromised mice. After 8 weeks, thetransplants were harvested, fixed in 4% PFA and then decalcified with 5%EDTA (pH 7.4), followed by paraffin embedding. The paraffin sectionswere stained with hematoxylin and eosin (H&E) and analyzed by an NIHImage-J. The newly-formed mineralized tissue area from five fields wascalculated and shown as a percentage to total tissue area.

In Vitro Osteogenic Differentiation Assay.

BMMSCs and tBMMSCs were cultured under osteogenic culture conditioncontaining 2 mM β-glycerophosphate (Sigma), 100 μM L-ascorbic acid2-phosphate and 10 nM dexamethasone (Sigma). After induction, thecultures were stained with alizarin red or alkaline phosphatase.

In Vitro Adipogenic Differentiation Assay.

For adipogenic induction, 500 nM isobutylmethylxanthine, 60 μMindomethacin, 500 nM hydrocortisone, 10 μg/ml insulin (Sigma), 100 nML-ascorbic acid phosphate were added into the culture medium. After 10days, the cultured cells were stained with Oil Red-O and positive cellswere quantified by using an NIH Image-J. Total RNA was also isolatedfrom cultures after 10 days induction for further experiments.

Reverse Transcriptase Polymerase Chain Reaction (RT-PCR) Analysis.

Extraction of total RNA and RT-PCR were performed according to standardprocedures.

Western Blotting Analysis.

20 mg of protein were used and SDS-PAGE and western blotting wereperformed according to standard procedures. β-actin on the same membraneserved as the loading control.

Inhibitor Treatment.

tBMMSCs and BMMSCs were treated with 1 mM L-NMMA (Cayman Chemical) or0.2 mM 1400 W (Cayman Chemical) to inhibit total NOS or iNOS,respectively. Aspirin 50 μg/ml (TAT) and telomerase inhibitor III (1 μM;EMD Chemicals) were used to activate and suppress telomerase activity incultured BMMSCs, respectively. CHIRON 99021 (1 or 10 μM; ChironCorporation) and Dickkopf 1 (DKK1, 10 ng/ml, R&D Systems) were used asan activator and inhibitor to regulate β catenin levels in BMMSCs.

Measurement of Telomerase Activity.

The Telomerase activity was measured using TeloTAGGG Telomerase PCRELISA kit (Roche).

Measurement of Nitric Oxide Production.

BMMSCs (0.2×10⁶/well) were cultured on 24-well plates with or withoutcytokines (IFNγ, 25 ng/ml; IL-1β, 5 ng/ml, R&D Systems) and chemicals(L-NMMA, 1 mM; 1400 W, 0.2 mM; aspirin, 50 μg/ml; Telomerase inhibitorIII, 1 μM; CHIRON 99021, 1 or 10 μM; DKK1, 10 ng/ml) at indicatedconcentration and days. The same chemical concentration was also used incombination treatment such as DKK and aspirin or Telomerase inhibitorand CHIRON99021. The supernatant from each culture was collected andmeasured nitric oxide concentration using Total Nitric Oxide andNitrate/Nitrite Parameter Assay kit (R&D Systems) according tomanufacturer's instruction.

Cell Apoptosis and Cell Survival Assay.

Transwell system (Corning) was used for co-culture experiments. 0.2×10⁶of tBMMSCs or BMMSCs were seeded on each lower chamber. In the upperchambers, activated splenocytes (1×10⁶/chamber), which werepre-stimulated with plate-bounded anti CD3c antibody (5 μg/ml) andsoluble anti CD28 antibody (2 μg/ml) for 3 days, were loaded. Bothchambers were filled with a complete medium containing Dulbecco'sModified Eagle Medium (DMEM, Lonza) with 10% heat-inactivated FBS, 50 μM2-mercaptoethanol, 10 mM HEPES, 1 mM sodium pyruvate (Sigma), 1%non-essential amino acid (Cambrex), 2 mM L-glutamine, 100 U/mlpenicillin and 100 mg/ml streptomycin. To measure the splenocyteviability, cell counting kit-8 (Dojindo Molecular Technoloies) wereused. For apoptosis of splenocyte analysis, Annexin V-PE apoptosisdetection kit I (BD Bioscience) were used and analyzed on FACS^(Caliber)(BD Bioscience).

In Vitro CD4⁺CD25⁺Foxp3⁺Tregs Induction.

CD4⁺CD25⁻ T-lymphocytes (1×10⁶/well), collected by CD4⁺CD25⁺regulatoryT-cell Isolation kit (Miltenyi Biotec), were pre-stimulated with platebounded anti CD3c antibody (5 μg/ml) and soluble anti CD28 antibody (2μg/ml) for 3 days. These activated T-lymphocytes were loaded on 0.2×10⁶of BMMSC or tBMMSC cultures with recombinant human TFGβ1 (2 μg/ml) (R&DSystems) and recombinant mouse IL2 (2 μg/ml) (R&D Systems). After 3days, cells in suspension were collected and stained with antiCD4-PerCP, anti CD8a-FITC, anti CD25-APC antibodies (each 1 μg) for 45min on ice under dark condition. And then cells were stained with antiFoxp3-PE antibody (1 μg) using Foxp3 staining buffer kit (eBioscience)for cell fixation and permeabilization. The cells were analyzed onFACS^(Calibur) (BD Bioscience).

Allogenic mouse tBMMSC transplantation into MRL/Ipr mice. Under generalanesthesia, C3H/HeJ-derived BMMSCs or tBMMSCs (0.1×10⁶ cells/10 g bodyweight) were infused into MRL/lpr mice via tail vein at 10 weeks old age(n=6). In control group, MRL/lpr mice received PBS (n=5). All mice weresacrificed at 12 weeks old age for further analysis. The proteinconcentration in urine was measured using Bio-Rad Protein Assay(Bio-Rad,). The number of white blood cells from peripheral blood wasmeasured by Coulter LH-750 (BECKMAN Coulter).

Measurement of Autoantibodies, Albumin, sRANKL and CTX.

Peripheral blood serum samples were collected from mice. Autoantibodies,albumin, sRANKL and CTX were analyzed by enzyme-linked immunosorbentassay (ELISA) method using commercial available kits (anti-dsDNAantibodies, ANA, and albumin, alpha diagnostic; sRANKL, R&D Systems;CTX, Nordic Bioscience Diagnostics A/S) according to their manufactures'instructions. The results were averaged in each group. The intra-groupdifferences were calculated between the mean values.

TRAP Staining.

Deparaffinized sections were re-fixed with a mixture of 50% ethanol and50% acetone for 10 min. TRAP-staining solutions were freshly made (1.6%naphthol AS-BI phosphate in N, N-dimethylformamide and 0.14% fastred-violet LB diazonium salt, 0.097% tartaric acid and 0.04% MgCl₂ in0.2 M sodium acetate buffer, pH 5.0) and mixed in 1:10. The sectionswere incubated in the solution for 10 min at 37° C. under shield andcounterstained with toluidine blue. All regents for TRAP staining werepurchased from Sigma.

Histometry.

Area of trabecular bone was measured on bone sections with H&E staining.To quantify osteoclast activity in the bones, number of matureosteoclasts was determined by TRAP positive cells attached on the bonesurface. Each number of cells and area were measured from fiverepresentative images per each sample using an NIH Image-J, followed bycalculating the means. The data were average the means in eachexperimental group. The results were shown as each indicated percentage.

Rescue Lethal Dose Irradiated Mice.

In each group, 1×10⁶ cells in 50 ml PBS or PBS alone as control wereinjected into the tail vein of recipient mice at 1 day post lethalirradiation (8.5 Gy per mouse). The survival date of each mouse wasrecorded and analyzed.

Statistics.

Student's t-test was used to analyze statistic difference. The p valuesless than 0.05 were considered significant.

Example 1 A Subset of BMMSCs Fails to Adhere to Plastic Culture Dishes,but Attaches to ECM-Coated Culture Dishes

To determine whether a subset of BMMSCs remains in culture suspension,we seeded 15×10⁶ bone marrow all nuclear cells (ANCs) under regularplastic culture conditions for 2 days and subsequently transplanted allnon-attached cells into immunocompromised mice subcutaneously usinghydroxyapatite tricalcium phosphate (HA/TCP) as a carrier. At 8 weekspost-transplantation, newly formed bone was identified in thetransplants by H&E staining (FIG. 1A), suggesting that the BMMSC culturesuspension may contain cells with a capacity of differentiating intobone forming cells in vivo. Added evidence indicated that extracellularmatrix (ECM) produced by BMMSCs (BMMSC-ECM) can adhere higher numbers ofCFU-F when compared to plastic cultures (FIG. 10; Chen et al., 2007).Thus, we collected culture medium at 2 days post-primary CFU-F cultureand loaded the medium onto BMMSC-ECM-coated dishes (FIG. 1B). A subsetof BMMSCs (named tBMMSCs) in the suspension was able to adhere to theBMMSC-ECM and form CFU-F (FIG. 1B), at a lower incidence compared to thenumber of CFU-F generated from regular BMMSCs (FIG. 1C). tBMMSCs werefound to express mesenchymal stem cell associated markers (CD73, stemcell antigen 1 [Sca-1], Octamer 4 [Oct4], and stage specific antigen 4[SSEA4]) as evidenced by flow cytometric analysis (FIG. 1D). Whencompared with regular BMMSCs, tBMMSCs expressed significantly higherlevels of Sca-1 (87.74% vs. 52.16% in BMMSCs) and Oct4 (40.7% vs. 14.08%in BMMSCs), both earlier progenitor surface molecules for mesenchymalstem cells. In order to characterize stem cell properties of tBMMSCs, wecollected SSEA4 positive tBMMSCs and assessed their proliferation rateby bromodeoxyuridine (BrdU) labeling. We found that tBMMSCs had asignificantly elevated BrdU uptake rate compared to regular BMMSCs (FIG.1E). In addition, we used a continuous cell culture assay to indicatethat SSEA4⁺ tBMMSCs acquired a significantly increased number ofpopulation doubling (FIG. 1F). These data imply that tBMMSCs aredistinct from regular BMMSCs in terms of attachment, proliferation, andself-renewal.

To examine the multipotent differentiation potential, we revealed thattBMMSCs are analogous to BMMSCs in expression of alkaline phosphatase(ALP), mineralized nodule accumulation under the osteogenic inductivecultures, and bone regeneration when transplanted into immunocompromisedmice using HA/TCP as a carrier (FIGS. 11A, 11B). Furthermore, we showedthat tBMMSCs were similar to regular BMMSCs in forming Oil red 0positive cells under adipogenic inductive conditions, expression ofadipogenic genes peroxisome proliferator-activated receptor gamma 2(PPARγ2) and lipoprotein lipase (LPL), and differentiating intochondrocytes under the chondrogenic inductive conditions with expressionof proteoglycan, trichrome positive collagen, and type II collagen(FIGS. 11C, 11D). These data confirm that tBMMSCs are a novel subset ofnon-adherent BMMSCs.

Example 2 tBMMSCS Express Telomerase and CD34, but are Distinct fromHematopoietic Stem Cells

In order to characterize tBMMSCs, flow cytometric analysis was used toexamine whether tBMMSC expressed hematopoietic cell markers. We foundthat 17.4% of tBMMSCs, but not regular BMMSCs, expressed CD34, a HSC andendothelial cell marker (FIG. 2A). BMMSCs (21.25%) and tBMMSCs (31.22%)expressed CD45, another hematopoietic marker, at passage 2 (FIG. 2A).Both BMMSCs and tBMMSCs were negative to CD11b antibody staining (datanot shown), excluding that tBMMSCs are derived from monocyte/macrophagelineage cells. Importantly, CD34⁺ tBMMSCs co-expressed BMMSC associatedmarkers (CD73 or Oct4), as evidenced by flow cytometric analysis (FIG.2B). Western blot analysis confirmed that tBMMSCs expressed CD34, CD73,and CD105 (FIG. 2C), and regular BMMSCs expressed CD73 and CD105, butlacked expression of CD34 (FIG. 2C). tBMMSCs show a continued expressionof CD34 from passage 1 to 5, however, the expression levels appearreduced after passage 3 (FIG. 2D). To further verify CD34 expression intBMMSCs, we used double immunocytostaining to show that tBMMSCsco-express CD34 with mesenchymal markers CD73 and CD105 (FIGS. 2E, 2F)and regular BMMSCs are negative for anti-CD34 antibody staining (FIGS.2E, 2F). More interestingly, we found that tBMMSCs possessedsignificantly higher levels of telomerase activity compared to regularBMMSCs by PCR-ELISA assay and Western blot analysis (FIGS. 2G, 2H),implicating that tBMMSCs may be a primitive subpopulation of BMMSCs.

Next, we used flow cytometry to sort CD34 and CD73 double-positive cellsfrom bone marrow ANCs and recovered 3.77% double-positive cells (FIG.2I). These CD34 and CD73 double-positive cells exhibit mesenchymal stemcell characteristics, including forming single colony clusters (FIG. 2J)and differentiating into osteogenic and adipogenic cells (data notshown), indicating a feasible approach of directly isolating tBMMSC-likecells from bone marrow. CD34⁺/CD73⁺ BMMSCs are analogous to tBMMSCs interms of having higher level of telomerase activity and high NOproduction when compared to regular BMMSCs (FIGS. 2K, 2L).

To exclude potential HSC contamination in tBMMSCs, we used aspirin (TAT)to elevate telomerase level in regular CD34⁻ BMMSCs (FIG. 7C). After theaspirin treatment, BMMSCs exhibit higher levels of Sca-1 and Oct4expression when compared to BMMSCs, but at a lower level than tBMMSCs(FIG. 3A, 3B). Importantly, aspirin (TAT)-treated CD34⁻ BMMSCs acquire apositive CD34 expression (FIG. 3A). Western blot analysis confirmed thataspirin (TAT)-treated BMMSCs express CD34, but at a lower level thantBMMSCs (FIG. 3C). These data suggest that CD34 expression in BMMSCs isnot due to HSC contamination.

It is generally believed that CD34 expression is associated with HSCsand endothelial populations. HSCs can differentiate into hematopoieticcell lineage and rescue lethal dose-irradiated subjects. Thus, we usehematopoietic differentiation medium to treat tBMMSCs, aspirin(TAT)-treated BMMSCs and regular BMMSCs and find all of these cells failto differentiate into hematopoietic cell lineage as seen in bone marrowcells and linage cells served as positive controls capable of formingcolony clusters (FIG. 4A). Next, we infused tBMMSC systemically torescue lethal dose-irradiated mice and found that tBMMSCs, but notregular BMMSCs, can extend the lifespan of lethal dose-irradiated mice(FIG. 4B). However, tBMMSCs failed to rescue lethal dose-irradiatedmice, as shown in bone marrow group (FIG. 4B). These experimentalevidences further indicate that CD34 expression in tBMMSCs is not due toHSC contamination.

Example 3 tBMMSCS Possess Superior Immunomodulatory Functions Via HighNitric Oxide (No) Production

Recently, immunomodulatory properties were identified as an importantstem cell characteristic of BMMSCs, leading to utilize systemic infusedBMMSCs to treat a variety of immune diseases (Nauta et al., 2007;Uccelli et al., 2007, 2008). Here we found that tBMMSCs exhibited asignificant increased capacity for NO production compared to regularBMMSCs when treated with interferon gamma (IFNγ) and interleukin 1 beta(IL-1β) (FIG. 5A). It is known that NO plays a critical role inBMMSC-mediated immunosuppression (Ren et al., 2008), therefore, weassessed the functional role of high NO production in tBMMSC-associatedimmunomodulatory properties. Spleen (SP) cells were activated withstimulation of anti-CD3 and anti-CD28 antibodies for 3 days and thenco-cultured with tBMMSCs or regular BMMSCs in the presence of thegeneral nitric oxide synthase (NOS) inhibitor, NG-monomethyl-L-arginine(L-NMMA), or the inducible NOS (iNOS) inhibitor, 1400 W, using aTranswell culture system. The efficacy of L-NMMA and 1400 W to inhibitNO production in BMMSCs was verified (FIG. 12). Although both tBMMSCsand regular BMMSCs were capable of inhibiting cell viability ofactivated SP cells, tBMMSCs showed a marked inhibition of SP cellviability over that of regular BMMSCs (FIG. 5B). Interestingly, bothL-NMMA and 1400 W were able to significantly block tBMMSC, but notregular BMMSC, induced cell viability of activated SP cells (FIGS. 5C,5D). Furthermore, flow cytometric analysis indicated that both tBMMSCsand regular BMMSCs induce apoptosis of activated SP cells in theTranswell culture system, including early apoptotic cells (FIG. 5E) andlate apoptotic and dead cells (FIG. 5H). However, tBMMSCs show anelevated capacity in inducing activated SP cell apoptosis compared toregular BMMSCs (FIGS. 5E, 5H). When L-NMMA and 1400 W were added to thecultures, the number of early and late apoptotic SP cells wassignificantly reduced in both tBMMSC and regular BMMSC groups (FIGS. 5F,5G, 5I, 5J). Treatment with 1400 W resulted in a significantly greaterinhibition of early apoptotic SP cells in tBMMSC group compared to theregular BMMSC group (FIG. 5G). These data suggest that NO production isrequired for BMMSC-mediated immunomodulation.

Next, we co-cultured naïve⁻T-cells with tBMMSCs or regular BMMSCs in thepresence of IL-2 and transforming growth factor beta 1 (TGF-β1). Wefound that tBMMSCs showed a significant up-regulation of CD4⁺CD25⁺Foxp3⁺regulatory T cell (Tregs) levels when compared to regular BMMSCs (FIG.5K). Both L-NMMA and 1400 W were able to inhibit BMMSC- andtBMMSC-induced up-regulation of Tregs, as shown by flow cytometricanalysis (FIGS. 5L, 5M). The regulatory effect on Tregs was moresignificant in the tBMMSC group compared to the BMMSC group (FIGS. 5L,5M). These data further verified the role of NO in tBMMSC-inducedimmunomodulatory effect.

Example 4 tBMMSCS Transplantation Improves Multiple Organ Function inMRL/LPR Mice

In order to examine in vivo immunomodulatory properties of tBMMSCs, weinfused allogenic tBMMSCs and BMMSCs into MRL/lpr mice at 10 weeks ofage and analyzed treatment response at 12 weeks of age (FIG. 6A). Wefound that both tBMMSCs and BMMSCs were capable of improving SLE-inducedglomerular basal membrane disorder (FIG. 6B) and reducing the urineprotein level (FIG. 6C). It appeared that tBMMSCs were superior comparedto BMMSCs in terms of reducing the overall urine protein levels (FIG.6C). As expected, MRL/lpr mice showed remarkable increase in the levelsof autoantibodies, including anti-double strand DNA (dsDNA) IgG and IgMantibodies (FIGS. 6D, 6E), and anti-nuclear antibody (ANA; FIG. 6F) inthe peripheral blood. Although tBMMSC and BMMSC infusion showedsignificant decreased levels of dsDNA IgG, IgM antibodies and ANA inperipheral blood (FIGS. 6D-F), tBMMSCs showed superior therapeuticeffect in reducing dsDNA IgG antibody and ANA levels when compared toBMMSC group (FIGS. 6D, 6F). Additionally, decreased serum albumin levelsin MRL/lpr mice were recovered by tBMMSC and BMMSC infusion (FIG. 6G),but tBMMSC treatment results in more significant recovery than BMMSCtreatment (FIG. 6G).

Next, we used flow cytometric analysis to reveal that tBMMSC show moreeffectiveness in recovering the decreased level of CD4⁺CD25⁺Foxp3⁺ Tregsand increased number of CD4⁺IL17⁺IFNγ⁻T-lymphocytes in peripheral bloodwhen compared to BMMSCs (FIG. 6H, 6I). Furthermore, we showed thattBMMSCs are superior to BMMSCs in terms of reducing increased number oftartrate-resistant acid phosphatase (TRAP) positive osteoclasts in thedistal femur epiphysis of MRL/Ipr mice (FIG. 13A), elevated serum levelsof soluble runt-related NF-κB ligand (sRANKL), a critical factor forosteoclastogenesis, (FIG. 13B) and bone resorption marker C-terminaltelopeptides of type I collagen (CTX, FIG. 13C). These data suggest thattBMMSCs show superior therapeutic effect for SLE disorders compared toBMMSCs.

Example 5 No Production in BMMSCs is Modulated by Telomerase ActivityCoupled with WNT/β-Catenin Signaling

Since elevated NO production telomerase activity were observed intBMMSCs, it is important to elucidate whether telomerase activitygoverns NO production in tBMMSCs. We found that telomerase inhibitor IIIis effective in inhibiting telomerase activity along with reducing NOproduction in tBMMSCs (FIGS. 7A, 7B). Similar effects of the telomeraseinhibitor were also found in regular BMMSCs (FIG. 7C, 7E). In contrast,aspirin (TAT) treatment leads to a significantly elevated telomeraseactivity, telomerase reverse transcriptase (TERT) expression and NOproduction in BMMSCs (FIG. 7C-E). These data imply that telomeraseactivity may be associated with NO production in BMMSCs.

Recently, it was reported that telomerase directly modulatesWnt/beta-catenin signaling by serving as a cofactor in a beta-catenintranscriptional complex (Park et al., 2009). Thus, we assessed whethertelomerase activity-associated NO production in BMMSCs could bedown-regulated by the Wnt inhibitor, Dickkopf 1 (DKK1). Interestingly,we found that DKK1 was able to significantly block aspirin-induced NOproduction in BMMSCs when added to the cultures prior to the aspirin(TAT) treatment (FIG. 7F). The efficacy of DKK1 in reducing activatedβ-catenin level was confirmed by Western blot analysis (FIG. 7G).Moreover, we found that aspirin (TAT) was able to partially blockDKK1-induced down-regulation of activated beta-catenin (FIG. 7G). Inorder to examine the mechanism by which DKK1 inhibits aspirin(TAT)-induced NO production, we showed that DKK1 is capable of blockingaspirin (TAT)-induced telomerase activity (FIG. 7H). These data indicatethat telomerase-driven NO production is coupled with Wnt/β-cateninsignaling.

Next, we determined whether Wnt/beta-catenin signaling affected NOproduction in BMMSCs. We used Chiron 99021 (Chiron) to treat BMMSCs for7 days and showed elevation of active beta-catenin in a dose-dependentmanner (FIG. 7I), confirming efficacy of Chiron as a Wnt/beta-cateninactivator. We then showed that Chiron treatment up-regulated NOproduction in BMMSCs in a dose-dependent manner (FIG. 7J), along with anelevated telomerase activity in BMMSCs (FIG. 7K). Further, we showedthat Chiron-induced telomerase activity and NO production could beblocked by 3 days of pre-treatment with telomerase inhibitor III (FIGS.7K, 7L). These findings suggest that telomerase and Wnt/beta-catenincollaboratively enhance telomerase activity and induce NO production inBMMSCs.

Example 6 Aspirin Treatment Generates Immunomodulatory Activated BMMSCs

In order to determine whether telomerase affects immunomodulatoryproperties of regular BMMSCs, we showed that aspirin (TAT) is able topromote BMMSC-induced reduction of activated SP cell viability andelevation of early and late apoptosis of activated SP cells (FIGS.14A-14C). These data suggest a potential of inducing telomerase activityin regular BMMSC to improve their immunomodulatory functions, as seen intBMMSCs.

In order to confirm therapeutic effect of aspirin (TAT)-treated BMMSCs(TAT-BMMSC), we infused either 0.1×10⁶ or 0.01×10⁶TAT-BMMSC into MRL/lprmice at 10 weeks of age and analyzed treatment response at 12 weeks ofage. We found that both aspirin treated TAT-BMMSC and BMMSC were capableof reducing the urine protein level when compared to MRL/lpr mice (FIG.8A). TAT-BMMSC were more effective in reducing the overall urine proteinlevels at both 0.1×10⁶ and 0.01×10⁶ groups when compared to BMMSC. Itappeared that infusion of 0.01×10⁶ BMMSCs fail to significantly reduceurine protein levels (FIG. 8A). Although TAT-BMMSC and BMMSC infusionshowed significant decreased levels of dsDNA IgG, IgM antibodies and ANAin peripheral blood (FIGS. 8B-D), TAT-BMMSC showed superior therapeuticeffect in reducing dsDNA IgG and IgM antibodies and ANA levels whencompared to BMMSC group at both 0.1×10⁶ and 0.01×10⁶ groups (FIGS.8B-D). Additionally, ELISA and flow cytometric analysis revealed thatTAT-BMMSC show more effectiveness in reducing serum IL17 levels in0.01×10⁶ group (FIG. 8E) and number of CD4⁺IL17⁺IFNγ⁻T-lymphocytes inboth 0.1×10⁶ and 0.01×10⁶ groups (FIG. 8F) and elevating the level ofCD4⁺CD25⁺Foxp3⁺ Tregs in 0.01×10⁶ group when compared to BMMSCs (FIG.8G). These data indicate that the number of BMMSCs in immuno-therapycould be significantly reduced with ex vivo telomerase activatortreatment.

Example 7

Human bone marrow contain tBMMSCs and aspirin treatment can induceregular human BMMSC to become tBMMSCs with improved immunomodulatoryfunction. When aspirin was added into culture medium at 2.5 μg/ml or 50μg/ml for 1 week, there is a significantly increased level of telomeraseactivity in BMMSCs.

While various aspects and embodiments have been disclosed herein, otheraspects and embodiments will be apparent to those skilled in the art.The various aspects and embodiments disclosed herein are for purposes ofillustration and are not intended to be limiting, with the true scopeand spirit being indicated by the following claims. Those skilled in theart will recognize, or be able to ascertain using no more than routineexperimentation, many equivalents to the specific embodiments of themethod and compositions described herein. Such equivalents are intendedto be encompassed by the following claims.

All references cited herein, including but not limited to patents,patent applications, and non-patent literature, are hereby incorporatedby reference herein in their entirety.

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We claim:
 1. A method of modulating immune system of a human patientcomprising administering to the patient a therapeutically effectiveamount of isolated high telomerase human bone marrow mesenchymal stemcells.
 2. The method of claim 1, wherein the isolated high telomerasehuman bone marrow mesenchymal stem cells are prepared by treating humanbone marrow mesenchymal stem cells with an effective amount oftelomerase inducing agent.
 3. The method of claim 2, wherein thetelomerase inducing agent comprises aspirin or a compound with similarchemical structure.
 4. The method of claim 2, wherein the telomeraseinducing agent comprises aspirin.
 5. The method of claim 4, whereinamount of aspirin used in the treatment of human bone marrow mesenchymalstem cells is in the range of 2 micrograms/milliliter to 50micrograms/milliliter.
 6. The method of claim 5, wherein the human bonemarrow mesenchymal stem cells are treated with aspirin for about oneweek.
 7. The method of claim 2, wherein the human bone marrowmesenchymal stem cells are treated with an effective amount oftelomerase inducing agent ex-vivo.
 8. The method of claim 1, wherein thepatient has an immune disorder.
 9. The method of claim 1, wherein thepatient has systemic lupus erythematosus.